1. Field of the Invention
The present invention relates to an information processing apparatus including a plurality of storage devices, and a method of controlling the same.
2. Description of the Related Art
Recent information processing apparatuses are required to operate at low power, and various control methods have been proposed to reduce power consumption. In the computer industry, a mirroring technique is known, which holds identical data in a plurality of HDDs (Hard Disk Drives) to prevent a system down in case of a failure in one of the storage devices. Japanese Patent Laid-Open No. 2004-252570 proposes a system related to power control of a plurality of HDDs in mirroring.
To reduce power consumption, an interface unit (I/F) which is powered even in a low power state is used. This enables implementation of a power saving mode in which most parts of an information processing apparatus are powered off. More specifically, in the power saving mode, the I/F unit copes with a query from an external apparatus without resuming power supply to the entire information processing apparatus (e.g., Japanese Patent Laid-Open No. 2001-092603).
However, the above-described related arts have the following problems. For example, in the information processing apparatus described in Japanese Patent Laid-Open No. 2001-092603, upon receiving, from an external apparatus, a query or a request about information that is not held in the I/F unit, power supply to most part of the information processing apparatus needs to be resumed, resulting in an increase in power consumption. More specifically, the information processing apparatus sometimes receives data from an external apparatus connected via the I/F unit and stores it in the HDD. In this case, data storage in the HDD cannot be executed using only information held in the I/F unit or a memory for data storage. For this reason, if such a request is received, it is necessary to resume power supply to process blocks necessary in the information processing apparatus including the HDD. This increases power consumption.
In mirroring for always storing identical data in a plurality of HDDs to ensure their reliability, the HDDs used for mirroring increase power consumption.